Abstract
This paper presents the analysis and design of a variable frequency and phase-shift controlled series-resonant converter applied as a power source for an electric arc welding machine with output ratings of 30 V and 130A. The main switches of this converter always hold zero-voltage switching (ZVS) from very light to full load. The conventional filter inductor is removed so as the assumption of a constant current sink is no longer valid, thus complicating the analyses dramatically. The operational principles of the converter applied in a welding machine design are described in detail from which the voltage and current stresses imposed on the main components can be, therefore, derived and the design procedure can be outlined as well. Computer simulations and experimental results obtained from a laboratorical prototype are illustrated to confirm the analytical works.